fetiship
A relationship between sexual and/or romantic partners wherein the participants don't admit to or have awareness of the fact that the premise of the relationship is entirely based on a sexual fetish.
T: "He loves me for me, we're in a committed relationship."
M: "He loves you because you're dangerously, morbidly obese and he gets off to it; you're in a fetiship."
M: "He loves you because you're dangerously, morbidly obese and he gets off to it; you're in a fetiship."